Preschool-aged foster children are at high risk for numerous negative outcomes, and these risks are heightened for children who experience foster placement disruptions. However, there is very limited use of evidence-based interventions for young children in the child welfare system. Major barriers to progress in this area include a lack of available evidence-based programs for foster children across the preschool years and the tendency for the few existing evidence-based interventions to be resource intensive in terms of funding and the level of staff expertise required to be implemented with fidelity. Readily scalable, evidence-based interventions for foster preschoolers are clearly needed to reduce the widespread disparities. The goal of the proposed study is to conduct a randomized clinical trial of a new, low-cost, manualized, group-based intervention for foster preschoolers and their caregivers. We propose to evaluate two versions of the intervention: (a) a basic version that employs a curriculum consisting of 16 weekly psychoeducational foster/kinship caregiver support groups and (b) an augmented version that consists of the caregiver support groups and 16 weekly, curriculum-based, child playgroups targeting executive functioning, early literacy, and socioemotional development. Across four waves of data collection (baseline, immediately post intervention, and 12 and 18 months post baseline), we will examine the extent to which the two intervention conditions show improved parenting, reduced rates of disrupted placements, and improved child outcomes. We will conduct multivariate modeling to examine mediating mechanisms underlying the hypothesized immediate and longer- term intervention effects. Finally, we will conduct a comprehensive economic evaluation to examine the incremental costs associated with implementing each intervention condition (compared to services as usual) and the benefits realized in the intervention conditions in terms of increased positive outcomes for children.